#include<iostream>
using namespace std;
int main(){
	/*
int A > 93;
int A < 100;
int B > 85;
int B < 92
int C > 70;
int C < 79;
int D > 62;
int D < 69;
int F > 1
int F < 60
*/
	int input;
	cout << "Please enter your grade" << endl;
		int x;
		cin >> x;

		if(x>100){
			cout<<" ERROR ";
		}
			else if(x<0){
			cout << " ERROR " ;
		}
	
		else if(x>93 && x<=100){
			cout << " A " << endl;
		}
	
		else if(x<=93 && x>85){
			cout << " B " << endl;
		}
		
		else if(x<=79 && x>70){
			cout << " C " << endl;
		}
		else if(x<69 && x>62){
			cout << " D " << endl;
		}
		else if(x<60){
			cout << " F " << endl;
		}
	

	system("pause");
	return 0;
}